Chevrolet Chevelle 1970 – SS 396 Convertible

Every 1970 SS 396 Chevelle is quietly lying to you — the badge says 396, but Chevrolet actually bored the engine out to 402 cubic inches that year. Here’s why the numbers stopped matching, and why it didn’t change a thing about how these cars perform.

This 1970 Chevelle SS 396 has some great features, ranging from the 350 HP 396 (402) under the hood, sport suspension, and SS appearance package, to the bucket seats, tilt wheel, air conditioning, and power convertible top.

Chevrolet told a small lie on every 1970 SS 396 badge it stamped, and the parenthetical in this car’s own description gives it away. That ‘(402)’ sitting quietly next to the ‘396’ isn’t a typo — it’s an admission that the engine badge and the engine itself stopped matching that year, and almost nobody who bought one ever noticed or cared. The reason behind that mismatch says a lot about how Detroit navigated emissions regulations in 1970, and why Chevrolet decided the SS 396 name was worth keeping even after the engine underneath it had quietly changed.

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Why ‘396’ Stopped Meaning 396

For 1970, Chevrolet bored the venerable 396 big-block out by .030 inches, bringing actual displacement to 402 cubic inches — technically a different engine than the one that had worn the 396 badge since 1965. Rather than rebrand the whole lineup and lose the marketing equity built up around ‘SS 396,’ Chevrolet simply kept the emblems as-is and let the badge lag behind the specs. Nobody has ever definitively nailed down the exact reason for the bore job, but the leading theory ties back to emissions rules of the era, which treated engines over 400 cubic inches differently than everything under that line — boring the 396 out to 402 may have been the path of least resistance rather than designing something new from scratch.

Same Badge, Same Performance

Here’s the part that matters most if you’re actually driving one: the extra six cubic inches changed nothing on the spec sheet. Horsepower and torque ratings carried over unchanged from 1969 to 1970, so a 350-horsepower ‘396’ in a 1970 Chevelle performs identically to its 1969 counterpart — the displacement bump was purely a badge-and-bore footnote, not a performance upgrade. Combined with the SS appearance package, sport suspension, and this particular car’s rare drop-top body style, that makes this Chevelle a genuine period-correct SS convertible wearing a slightly misleading engine badge for reasons that had nothing to do with power.

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